﻿/*
 * Copyright (c) 2015-2016 Constantijn Evenhuis (blueprints@const.nl)
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */
using Blueprints.Resolution;
using System;
using System.Collections.Generic;
using System.Reflection;

namespace Blueprints
{
    /// <summary>
    /// The default type provider, which provides all types from the assembly containing the root 
    /// type, and the types specified in the [Include] attributes on that type.
    /// </summary>
    public sealed class DefaultTypeProvider : ITypeProvider
    {
        private readonly Dictionary<Type, List<Type>> availableTypesByRootType = new Dictionary<Type, List<Type>>();

        /// <summary>
        /// Gets all discoverable types within the blueprint.
        /// </summary>
        /// <param name="rootType">The type of the root object in the blueprint.</param>
        /// <returns>All discoverable types within the blueprint.</returns>
        public IReadOnlyList<Type> GetAvailableTypes(Type rootType)
        {
            List<Type> availableTypes;
            if (!availableTypesByRootType.TryGetValue(rootType, out availableTypes))
            {
                TypeInfo typeInfo = rootType.GetTypeInfo();
                HashSet<Type> types = new HashSet<Type>(typeInfo.Assembly.ExportedTypes);
                foreach (DiscoverTypeAttribute include in typeInfo.GetCustomAttributes<DiscoverTypeAttribute>())
                {
                    foreach (Type type in include.Types)
                    {
                        types.Add(type);
                    }
                }

                availableTypes = new List<Type>(types);
                availableTypesByRootType[rootType] = availableTypes;
            }

            return availableTypes;
        }
    }
}